Bahram Qassemi extended condolences to the Russian government, people and bereaved families of the victims of the tragic incident, according to the Foreign Ministry’s official website.
Rescuers hunted for survivors on Wednesday in the rubble of the Russian apartment building wrecked by a New Year's Eve gas explosion, but found only bodies as the number of confirmed dead rose to 21, AFP reported.
Twenty people were still missing following the explosion, which destroyed 35 high-rise apartments in the Ural city of Magnitogorsk on Monday.
Braving temperatures that fell as low as minus 27 degrees Celsius (minus 16 degrees Fahrenheit), rescue workers were combing through mangled concrete and metal.
Their efforts were given a boost on Tuesday when a 10-month-old baby boy was found alive and reunited with his mother. But hope was starting to fade of finding many more survivors.
The emergency situations ministry said in a statement that as of 2:30 p.m. Moscow time (1130 GMT) the bodies of 21 people, including two children, had been recovered from the partly collapsed building.
Six people, including two children, had been rescued.
The explosion, believed to have been caused by a gas leak, tore through the 10-story building in the industrial town nearly 1,700 kilometers (1,050 miles) east of Moscow, in the early hours of Monday.
The Soviet-era apartment block was home to about 1,100 people and the explosion left dozens homeless over the New Year – the biggest holiday of the year in Russia.